Pharmacokinetic Profile of Oral Magnesium Hydroxide

Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

Effect of alkalizing agent on abuse deterrent potential of multiple-unit ingestion of bilayer abuse-deterrent extended-release tablets using propranolol as model drug for opioids overdose crisis

The objective of present study is to develop bilayer abuse-deterrent extended-release tablets (ADERTs) using propranolol HCl as model drug for opioids overdose crisis. Bilayer ADERTs were fabricated by direct compression and formulated with polymer matrix in extended-release drug layer coupled with alkalizing and aversive agents in fast-disintegrating pH modifying layer. Various alkalizing agents, like magnesium hydroxide, aluminum hydroxide, calcium carbonate, and calcium hydroxide, were evaluated for their abuse-deterrent potential via in-vitro drug release and extraction studies. Based on the outcomes, magnesium hydroxide was selected as an alkalizing agent, since it raised the pH of dissolving media near to pKa of the drug studied in this investigation. The formulated bilayer ADERTs with magnesium hydroxide provided similar drug release profiles as compared to conventional extended-release tablets for single-unit ingestion. However, upon ingestion of multiple-unit bilayer ADERTs, the fast-disintegrating pH modifying layer increases pH of dissolving media, while extended-release layer increases micro-environmental pH within tablets. Retarding drug release owing to low solubility of basic drug at higher pH was observed. Therefore, the application of alkalizing agent has impact on pH-dependent solubility of drug like opioids and demonstrate its useful potential to be incorporated in bilayer ADERTs for opioids overdose crisis.

Oral absorption and drug interaction kinetics of moxifloxacin in an animal model of weightlessness

To investigate the effect of simulated weightlessness on the pharmacokinetics of orally administered moxifloxacin and the antacid Maalox or the antidiarrheal Pepto-Bismol using a tail-suspended (TS) rat model of microgravity. Fasted control and TS, jugular-vein-cannulated, male Sprague-Dawley rats received either a single 5 mg/kg intravenous dose or a single 10 mg/kg oral dose of moxifloxacin alone or with a 0.625 mL/kg oral dose of Maalox or a 1.43 mL/kg oral dose of Pepto-Bismol. Plasma concentrations of moxifloxacin were measured by HPLC. Pharmacokinetic data were analyzed using WinNonlin. Simulated weightlessness had no effect on moxifloxacin disposition after intravenous administration but significantly decreased the extent of moxifloxacin oral absorption. The coadministration of moxifloxacin with Maalox to either control or TS rats caused significant reductions in the rate and extent of moxifloxacin absorption. In contrast, the coadministration of moxifloxacin with Pepto-Bismol to TS rats had no significant effect on either the rate or the extent of moxifloxacin absorption. These interactions showed dose staggering when oral administrations of Pepto-Bismol and moxifloxacin were separated by 60 min in control rats but not in TS rats. Dose staggering was more apparent after the coadministration of Maalox and moxifloxacin in TS rats.

Predicting and Testing Bioavailability of Magnesium Supplements

Despite the presumption of the beneficial effects of magnesium supplementation, little is known about the pharmacokinetics of different magnesium formulations. We aimed to investigate the value of two in vitro approaches to predict bioavailability of magnesium and to validate this in subsequent in vivo testing. In vitro assessment of 15 commercially available magnesium formulations was performed by means of a Simulator of the Human Intestinal Microbial Ecosystem (SHIME^®) and by dissolution tests. Two magnesium formulations with contrasting bioavailability prediction from both in vitro tests (best vs. worst) were selected for in vivo testing in 30 subjects. In vivo bioavailability was compared following one acute ingestion by monitoring blood magnesium concentrations up to 6 h following intake. The in vitro tests showed a very wide variation in absorption and dissolution of the 15 magnesium products. In the in vivo testing, a significant different serum magnesium absorption profile was found up to 4 h following supplement ingestion for the two supplements with opposing in vitro test results. Moreover, maximal serum magnesium increase and total area under the curve were significantly different for both supplements (+6.2% vs. +4.6% and 6.87 vs. 0.31 mM.min, respectively). Collectively, poor bioaccessibility and bioavailability in the SHIME model clearly translated into poor dissolution and poor bioavailability in vivo. This provides a valid methodology for the prediction of in vivo bioavailability and effectiveness of micronutrients by specific in vitro approaches.

Magnesium Bioavailability and Tolerability Do Not Differ between Two Supplements with Different Release Properties

Magnesium (Mg²⁺) is one of the most frequently supplemented micronutrients. Due to possible gastrointestinal side effects, the European Food Safety Authority and the Institute of Medicine set the upper intake level for Mg²⁺ from supplements to 250 and 350 mg, respectively. Nevertheless, systematic data concerning the tolerability of Mg²⁺ supplements are scarce. The aim of the study was to directly compare the bioavailability and tolerability of two 500 mg Mg²⁺ supplements in a crossover study with duplicate determination. The different release properties were either a direct release (one phase) or a delayed release of the second half (two phases). An open-label, controlled trial with a crossover design, duplicate determination, and one-week washout phases was conducted. The participants ingested the test product after overnight fasting. Blood samples were taken at baseline and after 1, 2, 3, 4, 6, and 8 hours, and urine was collected over a period of 24 hours. The participants were on standardized nutrition during all examination days. There were no significant differences between the test products regarding 24-hour renal Mg²⁺ excretion and area under the curve of serum Mg²⁺ levels for 8 hours. Both test products were well tolerated with a very low frequency of gastrointestinal adverse effects and no significant differences between the test products. The Mg²⁺ bioavailability did not differ between the test products. The supplements examined had the same good tolerability. Both test products are therefore suited to enhance Mg²⁺ supply without relevant side effects.

Bioaccessibility and Bioavailability of a Marine-Derived Multimineral, Aquamin-Magnesium

Introduction: Magnesium is an essential mineral involved in a range of key biochemical pathways. Several magnesium supplements are present on the market and their degree of bioavailability differs depending on the form of magnesium salt used. Aquamin-Mg is a natural source of magnesium, containing 72 additional trace minerals derived from the clean waters off the Irish coast. However, the in vitro bioaccessibility and bioavailability of Aquamin-Mg in comparison with other supplement sources of magnesium has yet to be tested. Method: Aquamin-Mg, magnesium chloride (MgCl₂) and magnesium oxide (MgO) were subjected to gastrointestinal digestion according to the harmonized INFOGEST in vitro digestion method and in vitro bioavailability tested using the Caco-2 cell model. Magnesium concentration was measured by atomic absorption spectrophotometry (AAS). Results: Magnesium recovery from both Aquamin-Mg and MgCl₂ was greater than for MgO. Magnesium from all three sources was transported across the epithelial monolayer with Aquamin-Mg displaying a comparable profile to the more bioavailable MgCl₂. Conclusions: Our data support that magnesium derived from a marine-derived multimineral product is bioavailable to a significantly greater degree than MgO and displays a similar profile to the more bioavailable MgCl₂ and may offer additional health benefits given its multimineral profile.